Transvaginal phosphodiesterase inhibitors for infertility treatment

ABSTRACT

The present invention relates to a new application of phosphodiesterase inhibitors for couple infertility treatment which forms an effective alternative to the invasive assisted reproductive techniques such as conjugal artificial insemination and which consists of the transvaginal administration of a phosphodiesterase inhibitor immediately before and/or after coitus. It also relates to dosage forms suitable for the intravaginal administration of phosphodiesterase inhibitors.

TECHNICAL FIELD

The present invention relates to an alternative to the invasive assistedreproductive techniques for infertility treatment by administrating aphosphodiesterase inhibitor transvaginally.

State of the Prior Art

In developed countries it is calculated that approximately 15% of thecouples wishing to conceive a child have difficulties for achievingsame. A couple is considered infertile if the couple was incapable ofconceiving after having unprotected sexual relationships for at least 12months. As described, for example, in the document by Dohle et al.,Guidelines on Male Infertility (update 2010) published by the EuropeanAssociation of Urology, it is estimated that a male infertility factoris found in approximately 50% of the infertile couples. Male infertilityis mainly caused by poor semen quality due to causes which may be veryheterogeneous therefore, in practice, the cause of male infertility isoften unknown and is often referred to as idiopathic infertility. Inthese cases, an empirical medical treatment can be resorted to but saidtreatments tend to be long with varying effectiveness and are alwaysaccompanied by the risk of side effects associated with any prolongedoral pharmacological treatment. Therefore, it is often considered thatthe best option for these couples is to resort to assisted reproductivetechniques in attempt to have offspring.

Assisted reproductive techniques which infertile couples tend to resortto are conjugal artificial insemination (CAI) and in vitro fertilization(IVF). CAI consists of inseminating the semen of the couple itselfpreviously subjected to a sperm capacitation process by intrauterineroute so that the sperm acquire the ovule fertilizing capacity. IVF isbased on extracting oocytes from the woman and fertilizing them in vitrowith sperm from the partner which are also previously capacitated.

Even though the assisted reproductive techniques have become a verycommon practice in our society over the last decades they still have aseries of drawbacks.

First, assisted reproductive techniques are invasive techniques whichnecessarily require medical intervention to achieve conception and whichcan be troublesome for couples, beside the fact that, inevitably,pregnancy stops being the result of spontaneous sexual intercoursebetween a couple. Furthermore, said techniques have a high cost and amoderate percentage of success. Therefore, the article by Hernández etal., Registro de IAC-IAD de la Sociedad Espanõla de Fertilidad (CAI-AIDRegister of the Spanish Society of Fertility). Year 2003, RevistaIberoamericana de Fertilidad y Reproducción Humana (IberoamericanMagazine of Human Fertility and Reproduction), 2007, 24 (4):

229-240, for example, compiles the data from insemination registers(conjugal artificial insemination CAI and artificial insemination bydonor or AID) collected by the Spanish Society of Fertility in 2003 fromthe data supplied by 95 centers throughout Spain, and it is observedthat for couple insemination or CAI, the pregnancy rate is 14.7%. Forthe above reasons, it is found that many couples are reluctant toundergo the assisted reproductive techniques.

Within the scope of assisted reproductive techniques, the state of theart describes the in vitro use of pentoxifylline, a non-specificphosphodiesterase enzyme inhibitor, for the treatment of sperm samplesdue to its sperm motility improving capacity for the purpose ofimproving the capacitation of sperm intended to be used in saidtechniques either for in vitro fertilization or for artificialinsemination, as described, for example, in the article by Minhas etal., Effectiveness of pentoxifylline in semen preparation forintrauterine insemination, Hum. Reprod., 1996, 11 (6): 1236-9.

Likewise, the in vitro effect of selective phosphodiesterase PDE1 andPDE4 inhibitors in sperm extracts has also been studied. Selective PDE4inhibitors increase sperm motility whereas selective PDE1 inhibitorsstimulate acrosome reaction, such as described in the article by Fischet al., Enhancement of motility and acrosome reaction in humanspermatozoa: differential activation by type specific phosphodiesteraseinhibitors, Hum. Reprod. 1998; 13 (5): 1248-54.

On the other hand, the article by Aparicio et al., Pentoxifylline (BL191) by oral administration in the treatment of asthenozoospermia,Andrology, 1980, 12 (3): 228-31, describes the oral administration ofpentoxifylline for treating men with asthenozoospermia or low spermmotility. Said article describes a study where a high dose ofpentoxifylline was administrated to a group of 15 infertile men withasthenozoospermia, 1200 mg daily for four months. A substantialimprovement in sperm motility of the subjects treated was observed, and2 pregnancies (13.3%) were counted after the treatment. However,treatment with oral pentoxifylline, as typically occurs with anycontinuous pharmacological treatment, entails a certain risk of adverseeffects, particularly, among other possible side effects, it has beendescribed that pentoxifylline can induce hypotension and arrhythmias.Spanish Patent Application ES-A-2245609 describes that pentoxifylline orits metabolites can cause mutagenic effects.

International Patent Application WO-A-2004/037262 describes thetransvaginal administration of phosphodiesterase inhibitors for thepurpose of stimulating female sexual desire.

Therefore, there is still a need to provide an alternative for treatingcouple infertility, simple to use and non-invasive, respecting coupleintimacy and the natural conception process, while being effective, safeand economical.

OBJECT OF THE INVENTION

The object of the invention is the use of a phosphodiesterase inhibitorfor preparing a medicament intended for the transvaginal treatment ofcouples with infertility.

Another object of the invention is a phosphodiesterase inhibitor for usein the transvaginal treatment of couples with infertility.

Another object of the invention is a pharmaceutical composition of aphosphodiesterase inhibitor.

Another object of the invention is a kit including the composition of aphosphodiesterase inhibitor.

DETAILED DESCRIPTION OF THE INVENTION

The purpose of the present invention is to provide a phosphodiesteraseinhibitor administered transvaginally for use in treatment of coupleswith infertility.

The authors of the present invention have developed a new use forphosphodiesterase inhibitors through transvaginal administration, whichis significantly effective for infertility treatment, providing a safe,economical and easy-to-use treatment, whereby it forms an efficient andnon-invasive alternative to the assisted reproductive methods.

Phosphodiesterase Inhibitors

Phosphodiesterase inhibitors are a group of drugs which inhibit theaction of the enzymes from the family of cyclic-nucleotidephosphodiesterases (PDEs) that catalyze the hydrolysis of the innerphosphate bond of the cyclic monophosphate nucleotides cAMP (cyclicadenosine monophosphate) and cGMP (cyclic guanosine monophosphate). ThusPhosphodiesterase inhibitors act inhibiting the metabolism of secondintercellular messengers cAMP and cGMP.

The family of phosphodiesterases is made up of 11 groups sequentiallyknown as phosphodiesterase 1 (PDE1) to phosphodiesterase 11 (PDE11).Such drugs are selective inhibitors, i.e., drugs specifically inhibitingsome of said groups, as well as other drugs which are known asnon-specific or non-selective phosphodiesterase inhibitors, i.e., drugssimultaneously inhibiting more than one phosphodiesterase, have beendescribed.

Within the scope of the present invention, the term phosphodiesteraseinhibitors includes any inhibitory drug of said group of enzymes and itencompasses both non-specific phosphodiesterase inhibitors and selectiveinhibitors of any of the phosphodiesterases PDE1, PDE2, PDE3, PDE4,PDE5, PDE6, PDE7, PDE8, PDE9, PDE10 or PDE11, as well as mixtures ofmore than one phosphodiesterase inhibitor.

Among the selective inhibitors suitable for use in the scope of thepresent invention are, for example, selective phosphodiesterase 1 (PDE1)inhibitors such as, for example, vinpocetine; selectivephosphodiesterase 2 (PDE2) inhibitors such as, for example, EHNA(erythro-9-(2-hydroxy-3-nonyl)adenine); selective phosphodiesterase 3(PDE3) inhibitors such as, for example, milrinone, amrinone, enoxymone,cilostazol or cylostamide; selective phosphodiesterase 4 (PDE4)inhibitors such as, for example, rolipram, denbufylline, cilomilast androflumilast; or selective phosphodiesterase 5 (PDE5) inhibitors such as,for example, sildenafil, tadalafil or vardenafil, even though the latteralso interact with phosphodiesterase 6 since PDE5 and PDE6 arestructurally related.

Among the non-specific inhibitors suitable for use in the scope of thepresent invention are, for example, pentoxifylline, theophylline,theobromine, ibudilast, papaverine, and 3-isobutyl-1-methylxanthine,among others.

In a preferred embodiment of the invention, the phosphodiesteraseinhibitor is selected from the group consisting of a phosphodiesterase 1(PDE1) inhibitor, a phosphodiesterase 3 (PDE3) inhibitor, aphosphodiesterase 4 (PDE4) inhibitor and a non-selectivephosphodiesterase inhibitor, and a combination thereof.

In a more preferred embodiment, the phosphodiesterase inhibitor isselected from the group consisting of pentoxifylline, rolipram,milrinone and ibudilast.

In a particularly preferred embodiment of the invention, thephosphodiesterase inhibitor is pentoxifylline.

Rolipram is the international non-proprietary name (INN) designating theproduct 4-(3-cyclopentyloxy)-4-methoxyphenyl)-2-pyrrolidinone which is aselective phosphodiesterase 4 (PDE4) inhibitor.

Rolipram can be prepared, for example, as described in the Belgianpatent BE-A-826923.

Milrinone is the international non-proprietary name (INN) designatingthe product 1,6-dihydro-2-methyl-6-oxo-(3,4′-bipyridine)-5-carbonitrilewhich is a selective phosphodiesterase 3 (PDE3) inhibitor.

Milrinone can be prepared, for example, as described in the Belgianpatent BE-A-886336.

Ibudilast is the international non-proprietary name (INN) designatingthe product2-methyl-1-(2-(1-methyethyl)pyrazolo(1,5-a)pyridin-3-yl)-1-propanone. Itis a non-specific phosphodiesterase inhibitor inhibitingphosphodiesterases 3, 4, 10 and 11.

Ibudilast can be prepared, for example, as described German patentDE-A-2315801.

Pentoxifylline is the international non-proprietary name (INN)designating the product3,7-dihydro-3,7-dimethyl-1-(5-oxohexyl)-1H-purine-2,6-dione, a drugbelonging to the group of xanthines, particularly methylxanthines.

Pentoxifylline has been marketed for years to treat peripheral arterialdiseases and circulatory disorders due to its haemorrheologicalproperties capable of reducing blood viscosity and thus improvingperipheral blood circulation and enhancing venous return.

Likewise, it is known that pentoxifylline has a pharmacological actionas a non-specific phosphodiesterase inhibitor, capable of inhibitingphosphodiesterases PDE1-5, such as described, for example, in thearticle by Meskini et al. Phosphodiesterase inhibitory profile of somerelated xanthine derivatives pharmacologically active on the peripheralmicrocirculation. Biochem. Pharmacol. 1994; 47 (5): 781-8.

Pentoxifylline can be prepared, for example, as described in the UnitedStates patent U.S. Pat. No. 3,422,107.

In the context of the present invention, phosphodiesterase inhibitor isunderstood in a broad term and includes, in each case, its possiblepharmaceutically acceptable salts and/or solvates.

Particularly, for example, the names rolipram, milrinone, ibudilast andpentoxifylline also include their possible salts and/or solvates.

The phosphodiesterase inhibitor according to the present invention isnot administered according to a pre-established chronic administrationguideline, but according to a prompt treatment concomitantly with sexualintercourse, preferably at the time of maximum female fertility.

The dose of the phosphodiesterase inhibitor administered transvaginallyaccording to the present invention is comprised between 200 mg and 800mg of pentoxifylline in each administration, preferably comprisedbetween 300 mg and 600 mg, more preferably comprised between 350 mg and450 mg, and yet more preferably 400 mg of pentoxifylline.

Infertility

Couple fertility is defined as the couple capacity of having healthyoffspring through normal sexual activity.

In contrast, couple infertility is defined as the coupled incapacity forconceiving a child after attempting to do so for a certain determinedtime period.

According to the definition by WHO (World Health Organization),infertility is the inability of a sexually active couple who does notuse contraceptive methods to achieve pregnancy within one year period.Within the scope of reproductive medicine, this period is usuallyreduced to 6 months when the woman is 35 years old or more.

It is estimated that a male infertility factor is found in approximately50% of infertile couples. Male infertility is mostly caused by certainanomalies in semen characteristics even though at times it is alsoattributed to other causes such as, for example, an anomaly orobstruction in the genital tract, or an erectile or sexual dysfunction.

In the scope of the present invention, male infertility or infertilityof male origin refers to the infertility due to the existence of someanomaly in semen characteristics, such as a low sperm content(oligozoospermia), low sperm motility (asthenozoospermia orasthenospermia), an abnormal morphology (teratozoospermia), or acombination of the effects above (oligoasthenoteratozoospermia).

In the scope of the present invention, the expression “treatment ofcouples with infertility” refers to the infertility treatment ofsexually active couples who do not use contraceptive methods and whohave not achieved pregnancy after a time period considered as normal,usually 1 year or 6 months as defined previously; or to the treatment ofcouples in which the male has been diagnosed with male infertility dueto having an anomaly in the semen, regardless of the time elapsed sinceattempt to conceive is made.

In a preferred embodiment of the present invention, the use of thephosphodiesterase inhibitor is indicated for the treatment of coupleswith infertility substantially caused by male infertility, morepreferably due to an anomaly in the semen characteristics, and yet morepreferably due to asthenozoospermia.

In the scope of this invention, the term “treatment” applied to thecouples with infertility or to infertility, refers to the attempt toremedy the effect caused by said infertility, and it specifically refersto the couples' attempt to achieve a pregnancy and father offspring.

Likewise, in the scope of this invention, the term “infertility” isconsidered equivalent to the terms “sterility” or “subfertility”.

The authors of the present invention have surprisingly confirmed that ahigh percentage of pregnancies are achieved by means of the transvaginaladministration of phosphodiesterase inhibitory drugs in woman.Therefore, for example, as observed in the results of a study withpentoxifylline described in Example 3, after the transvaginaladministration of pentoxifylline, a pregnancy percentage of 20% wasachieved in couples with infertility substantially caused by maleinfertility. This percentage of success is significantly higher thanthat obtained by conjugal artificial insemination (14.7%) and evenhigher compared with that described for the oral administration ofpentoxifylline (13.3%), with the additional advantage of it being asimpler and non-invasive method which does not cause any type of allergyor side effect and which also maintains and even improves thecharacteristics of cervical mucus.

In general, couples with infertility susceptible to being treated withphosphodiesterase inhibitors according to the present invention arecouples who are candidates to be subjected to an assisted reproductivetechnique either by conjugal artificial insemination or by in vitrofertilization and who do not wish to undergo any of said invasivetechniques.

The use of phosphodiesterase inhibitors according to the presentinvention is an advantageous option with respect to the assistedreproductive techniques, since it is a non-invasive self-administrationtreatment respecting couple intimacy, and allowing conceiving naturallyafter sexual intercourse without altering the spontaneity of coitus.Furthermore, this treatment is more economical that the assistedreproductive techniques.

After performing a microscopic examination of the cervical exudate ormucus of women treated with pentoxifylline transvaginally, after 15 and20 hours from product administration, an improvement in sperm quality interms of motility is observed both in the case of asthenozoospermia andin the case of normospermia, a significant number of type A spermaccording to the WHO classification, i.e., sperm with rectilinearmovement at a speed greater than 25 μm/s being counted.

Likewise, said examination reveals an improvement in the characteristicsof cervical mucus in terms of its transparency, filancia(filament-forming capacity) and a leukocytic diathesis, even when is anadverse day of the genital cycle, or even when the woman is undertreatment with ovulation inducing drugs which negatively alter theproperties of cervical mucus.

Another object of the invention is a method for treating couples withinfertility comprising the administration of phosphodiesteraseinhibitors to the woman by intravaginal route.

According to the use of this invention, the phosphodiesterase inhibitor,in the form of a suitable pharmaceutical composition, must be introducedin the vaginal cavity. The administration is performed associated withsexual intercourse, preferably coinciding with the days of maximumfemale fertility, and can be administered before and/or after coitus,preferably immediately before or immediately after coitus, although afraction of the composition can be administered before coitus andanother fraction after, preferably, immediately before and immediatelyafter coitus. In the case of administrating the composition ofphosphodiesterase inhibitor in two fractions, the fraction administeredbefore coitus is comprised between 5% and 50% with respect to the totaldose applied and the fraction administered immediately after coitus iscomprised between 50% and 95% with respect to the total dose applied.

In the context of the invention, the term “immediately” refers to a timeperiod not more than 30 minutes, preferably not more than 15 minutes,and yet more preferably not more than 5 minutes.

After coitus and after applying the product, the woman preferablyremains in supine position for at least one hour.

To obtain greater treatment effectiveness, it is advisable to performthe treatment on the days of maximum female fertility. This can beperformed in a self-controlled manner by the couples, for example,through their knowledge of the menstrual cycle or through theobservation of the characteristics of vaginal mucus as an indicator ofthe more fertile days. In contrast, the most fertile days can also bedetermined by means of a vaginal ultrasound.

The gel can be administered in 3 different cycles or in several days ofthe same cycle.

In another embodiment of the invention, the phosphodiesterase inhibitorcan be administered in combination with an ovulation-inducing drug.Ovulation-inducing drugs include, for example, clomiphene, humangonadotropins, or human recombinant gonadotropins.

In another embodiment of the invention, the transvaginalphosphodiesterase inhibitor can be used as a complement to theartificial insemination technique for the purpose of increasing thechance of success thereof, i.e., of increasing the chance of achievingpregnancy. In this case, a specific amount of the composition containingthe phosphodiesterase inhibitor, preferably a semi-solid composition inthe form of cream, ointment, or gel is applied in any of the cupolasoccluding the uterine cervix after having performed the intrauterineinsemination. The semi-solid composition of the phosphodiesteraseinhibitor sometimes act as an occlusive stopper occluding those spermwhich would be lost in the plastic cupola, while at the same time allowsthe reactivation thereof to move upwards again towards the endometrialcavity. In another embodiment, an amount of the pharmaceuticalcomposition containing the phosphodiesterase inhibitor is placed at thevaginal fundus and the use of plastic cupolas in the uterine cervix isdisregarded.

Transvaginal Compositions of Phosphodiesterase Inhibitors

An object of the present invention is a pharmaceutical composition fortransvaginal administration comprising a phosphodiesterase inhibitor andat least one pharmaceutically acceptable excipient for use in thetreatment of couples with infertility.

In a preferred embodiment, the pharmaceutical composition comprises aphosphodiesterase inhibitor which is selected from the group consistingof a phosphodiesterase 1 (PDE1) inhibitor, a phosphodiesterase 3 (PDE3)inhibitor, a phosphodiesterase 4 (PDE4) inhibitor and a non-selectivephosphodiesterase inhibitor, and a combination thereof.

In a more preferred embodiment, the pharmaceutical composition comprisesa phosphodiesterase inhibitor which is selected from the groupconsisting of pentoxifylline, rolipram, milrinone and ibudilast.

In a particularly preferred embodiment, the pharmaceutical compositioncomprises pentoxifylline.

In the context of the present invention, the term “transvaginaladministration” is considered equivalent to “intravaginaladministration” or “vaginal administration”, and refers to theapplication of the drug inside the vagina, typically several centimeterstherein and it is preferably as deep as possible inside the vagina.

Most transvaginal dosage forms need an auxiliary device or an applicatorto achieve deep insertion as is already well known by the person skilledin the art.

The pharmaceutically acceptable forms for transvaginal administrationinclude solid forms, such as ovules, vaginal suppositories or vaginaltablets, as well as semi-solid forms such as creams, gels, ointments,pastes or foams, or in general any type of aqueous or non-aqueoussuspension or emulsion. Said pharmaceutical forms are prepared bymixing, dissolving or dispersing the phosphodiesterase inhibitor in apharmaceutically acceptable diluent carrier, and optionally adding atleast one excipient which is also pharmaceutically acceptable forintravaginal administration, according to the methods known by theperson skilled in the art, and as described, for example, in thepharmaceutical technology manual Remington The Science and Practice ofPharmacy, 20^(a) edition, Lippincott, Williams & Wilkins, Philadelphia,2000 [ISBN: 0-683-306472]. The carriers and/or excipients suitable forpreparing these pharmaceutically acceptable forms suitable fortransvaginal administration are described, for example, in the book byR. C. Rowe et al., Handbook of Pharmaceutical Excipients, 4^(a) edition,Pharmaceutical Press, London, 2003 [ISBN: 0-85369-472-9].

Therefore, for example, carriers suitable for preparing the vaginaltablets include lactose, sucrose, glucose, mannitol, sorbitol, celluloseor cellulose derivatives, among others, or a combination thereof. Thevaginal tablets preferably contain a disintegrating agent, and are morepreferably formulated with an effervescent base with carbonates and anorganic acid, such as citric acid or tartaric acid, for example.

The vaginal suppositories and vaginal ovules can be prepared, forexample, with carriers such as glycerin, cocoa butter, aglycerol-gelatin mixture, polyethylene glycol, polyethylene oxide, orsolid fats, such as for example, the commercial products known asWitepsol® made up of the mixtures of triglycerides, diglycerides andmonoglycerides, among others, or with a mixture thereof.

Creams, as is well known by the person skilled in pharmaceuticaltechnology, are semi-solid emulsions which can be oil-in-water (o/w)type or water-in-oil (w/o) type, formulated from an oily phase, anaqueous phase and an emulsifying agent. The oily phase is made up of acarrier which can be, for example, liquid paraffin or plant oil such as,for example, castor oil, almond oil, peanut oil, sesame oil, of cottonseed oil or corn oil.

Ointments are semi-solid fat preparations containing the dissolvedactive ingredient or are in the form of dispersion. Ointments can beformulated with various carriers such as paraffin, plastibases (mixtureof polyethylene with a series of hydrocarbons), plant oils, such as forexample, peanut oil, sesame oil, olive oil, cotton seed oil, almond oil,corn oil, silicones or polyethylene glycols, among others, or with amixture thereof. Pastes are prepared similarly to ointments and theyhave a more solid consistency due to that they contain higher amount ofinsoluble solid substances.

Foams are prepared according to methods well known by the person skilledin the art, usually by preparing a suspension of the active substance ina suitable carrier, preferably a plant or semi-synthetic oil, in thepresence of a thickening agent and subsequently putting said suspensionin a recipient closed with a valve through which a propellant isintroduced.

Gels are obtained from a liquid which is gelled by adding a rheologicagent or a gelling agent. Some gelling agents suitable for use in thepresent invention are, for example, carrageenan, guar gum, tragacanth,locust bean gum, pectin, agar, alginic acid, methylcellulose,hydroxyethylcellulose, hydroxypropyl methylcellulose,carboxymethylcellulose, carbomers, and polyethylene glycol, amongothers.

Gels can be hydrophobic which are also known as oleogels, in which thecarrier tends to be liquid paraffin or an oil; or hydrophilic, in whichthe carrier is water, a water soluble monohydroxy or polyhydroxyalcohol, or a hydroalcoholic mixture.

In the scope of this invention, gels, particularly hydrophilic gelsprepared preferably from a combination of water with a polyhydroxyalcohol are particularly preferred.

Another object of the present invention is a pharmaceutical compositionin the form of hydrophilic gel for transvaginal administrationcomprising a phosphodiesterase inhibitor, polyhydroxy alcohol, water,carbomer and alkaline agent.

The phosphodiesterase inhibitor is preferably selected from the groupconsisting of a phosphodiesterase 1 (PDE1) inhibitor, aphosphodiesterase 3 (PDE3) inhibitor, a phosphodiesterase 4 (PDE4)inhibitor and a non-selective phosphodiesterase inhibitor, and acombination thereof; more preferably, the phosphodiesterase inhibitor isselected from the group consisting of pentoxifylline, rolipram,milrinone and ibudilast; yet more preferably, the phosphodiesteraseinhibitor is pentoxifylline.

In a preferred embodiment, the composition consists essentially of aphosphodiesterase inhibitor, polyhydroxy alcohol, water, carbomer,alkaline agent and preservative.

The authors of the present invention have developed a composition of aphosphodiesterase inhibitor for transvaginal administration in the formof hydrophilic gel comprising a mixture of water and a polyhydroxyalcohol as the carrier, a carbomer as the gelling agent and an alkalineagent. This composition can be advantageously applied for the treatmentof couples with infertility.

The polyhydroxy alcohol is an alcohol containing more than one hydroxylgroup and for preparing the composition of the invention selection canbe made from the group consisting of propylene glycol,dipropyleneglycol, glycerin, 1,2,6-hexanetriol, sorbitol, polyethyleneglycol 100 (PEG100), polyethylene glycol 200 (PEG200), polyethyleneglycol 300 (PEG300) and polyethylene glycol 400 (PEG400). Propyleneglycol is preferably selected as the polyhydroxy alcohol.

A preferred gelling agent are carbomers which, as is well known by theperson skilled in the art, are cross-linked acrylic acid polymers.Cross-linking agents include sucrose allyl ether and pentaerythritolallyl ether.

Particularly preferred are carbomers aqueous solution, at 0.5% byweight/volume and at a pH value comprised between 6 and 11, of which hasa viscosity comprised between 25000 and 700000 mPa·s. Among thecarbomers which comply with this characteristic are carbomer 934,carbomer 934P and carbomer 940, sharing registration number CAS9003-01-4. These products are commercially available under the namesCarbopol® 934, Carbopol® 934P or Carbopol® 940. The most preferredcarbomer is carbomer 940, in aqueous solution, at 0.5% by weight/volumeand at a pH value comprised between 6 and 11, which has a viscositycomprised between 40000 and 60000 mPa·s.

It is well know that carbomers form acid colloidal dispersions when theyare dispersed in water having a pH value comprised between 2.5 and 3.5,being necessary to neutralize them with an alkaline agent so that theyacquire gel consistency. The alkaline agent is preferably selected fromthe group consisting of L-lysine, L-arginine, borax, potassiumhydroxide, sodium hydroxide, ammonia, sodium bicarbonate,aminomethylpropanol, tetrahydroxypropylethylenediamine, tromethamine,ethoxylated cocoamine (cocamine PEG15), diisopropanolamine,triisopropanolamine, and triethanolamine. More preferablytriethanolamine is used.

A preferred pharmaceutical composition for intravaginal administrationaccording to the present invention is a gel comprising aphosphodiesterase inhibitor, propylene glycol, carbomer, triethanolamineand water.

A particularly preferred pharmaceutical composition is a gel consistingessentially of a phosphodiesterase inhibitor, propylene glycol,carbomer, triethanolamine, water and preservative.

A preferred pharmaceutical composition comprises a phosphodiesteraseinhibitor in a proportion by weight comprised between 2% and 10%, morepreferably between 3% and 6%, and yet more preferably 4%; propyleneglycol in a proportion by weight comprised between 2% and 15%,preferably between 4% and 10%, and yet more preferably between 5% and7%; carbomer in a proportion by weight comprised between 0.5% and 2%,preferably between 0.75% and 1.5%, and yet more preferably between 0.9%and 1.2%; triethanolamine in a proportion by weight comprised between0.1% and 1%, preferably between 0.2% and 0.8%, and yet more preferablybetween 0.3% and 0.6%; and water in a proportion by weight comprisedbetween 75% and 95%, more preferably between 80% and 92%, and yet morepreferably between 85% and 90%.

In the composition of the invention, the sum of the percentages byweight of the components is 100%.

The pH of the gel is preferably comprised between 5.5 and 7.5, morepreferably comprised between 6 and 6.5.

The phosphodiesterase inhibitor is preferably selected from the groupconsisting of a phosphodiesterase 1 (PDE1) inhibitor, aphosphodiesterase 3 (PDE3) inhibitor, a phosphodiesterase 4 (PDE4)inhibitor and a non-selective phosphodiesterase inhibitor, and acombination thereof; more preferably, the phosphodiesterase inhibitor isselected from the group consisting of pentoxifylline, rolipram,milrinone and ibudilast; yet more preferably, the phosphodiesteraseinhibitor is pentoxifylline.

The authors of the present invention have observed that theadministration of the phosphodiesterase inhibitor in the form ofhydrophilic gel is particularly advantageous for the use of thisinvention, since said gel has the particularity that it is dissolvedupon contacting the semen, as a result of the natural liquefactionprocess experienced by semen after being deposited in the vagina.Therefore, with a hydrophilic gel, sperm released from the mucilaginouslayer of the semen can homogenously receive contact with thephosphodiesterase inhibitor in a particularly effective manner.

Optionally, the compositions for transvaginal application of the presentinvention can contain one or more additional excipients, for example,antioxidants, humectants, preservatives, thickeners, emollients,emulsifiers, pH-regulating agents, among others.

In the liquid or semi-solid compositions formulated using water as thecarrier, a preservative is generally included. Preferred preservativesinclude parabens (methylparaben, ethylparaben, propylparaben,butylparaben), benzalkonium chloride, and benzyl alcohol. Morepreferably a combination of propylparaben and methylparaben is used.

Kit

A kit including the composition of the invention and instructions foradministrating same is also part of the invention.

In a preferred embodiment, the kit includes three single-doses ofphosphodiesterase inhibitor between 200 mg and 800 mg in each of them,preferably between 300 mg and 600 mg, more preferably between 350 mg and450 mg, and yet more preferably 400 mg of phosphodiesterase inhibitor.

The phosphodiesterase inhibitor is preferably selected from the groupconsisting of a phosphodiesterase 1 (PDE1) inhibitor, aphosphodiesterase 3 (PDE3) inhibitor, a phosphodiesterase 4 (PDE4)inhibitor and a non-selective phosphodiesterase inhibitor, and acombination thereof; more preferably, the phosphodiesterase inhibitor isselected from the group consisting of pentoxifylline, rolipram,milrinone and ibudilast; yet more preferably, the phosphodiesteraseinhibitor is pentoxifylline.

The following indications for self-administration are preferred: thecouple must have sexual intercourse with vaginal ejaculation on the daysof maximum fertility, and must introduce the gel in the vaginal cavityimmediately after coitus with the applicator provided for such purpose,remaining in a supine position for at least one hour being advisable.

The most fertile days can be determined by means of using the methodscommon for that purpose, such as for example, cervical mucus test,vaginal ultrasound, or ovulation test.

Eventually, the composition of the invention can be administeredsimultaneously with an ovulation inducer.

The single-dose of the composition can be irrespectively administered in3 different cycles or in several days of the same cycle.

The following examples below are described for the purpose ofillustrating the invention, not for limiting same.

EXAMPLE 1 In Vitro Assay of the Effect of Milrinone, Ibudilast andPentoxifylline on Sperm Motility

In each case the corresponding phosphodiesterase inhibitor (rolipram,milrinone, ibudilast and pentoxifylline) was dissolved in a commercialmedium suitable for performing sperm preparations (SpermRinse®) to thedesired concentration. The SpermRinse® solution consists of abicarbonate and HEPES (N-2-(hydroxyethyl)piperazine-N′-ethanesulfonicacid) buffered medium containing human serum albumin.

A semen sample was taken from a patient with asthenozoospermia and itwas kept at room temperature for 5 minutes after liquefaction, it wasmixed with SpermRinse® solution without phosphodiesterase inhibitor in avolumetric ratio of 1:1.

Another part of the semen was mixed also after liquefaction with theSpermRinse® solution containing the phosphodiesterase inhibitor also ina proportion of 1:1 by volume.

For each observation, 3 microdrops of the preparation were used, theywere placed under an optical microscope with 20× objective and Maklercamera. A sperm count was performed, the number of type A sperm(advancing rapidly, with rectilinear trajectory) and type B sperm(advancing rapidly, with curvilinear trajectory) of each sample beingcounted. This was performed for the untreated sample and for the samplestreated with the phosphodiesterase inhibitor. Three readings were madefor each sample and the mean value was calculated.

Likewise, a subjective observation of the increase of sperm speed of allthe sperm types was also performed for the samples treated with thephosphodiesterase inhibitor, with respect to the untreated samples.

The results are summarized in the following table:

Product Increase in sperm Increase in sperm (concentration) type A + Bspeed Pentoxifylline (1 μM) ++ ++ Milrinone (1 μM) ++ ++ Ibudilast (100μM) ++ ++

Second column corresponds to the increase observed in fast sperm, thesymbol ++ indicates an increase greater than 40% in the A+B sperm typecount.

Third column corresponds to the increase in the individual speed of allthe sperm types, the rating was subjectively assigned depending on theincrease in the motility observed, such that the symbol ++ denotes avery significant increase in sperm motility.

EXAMPLE 2 Preparation of a Pentoxifylline Gel for TransvaginalAdministration

The following ingredients were used for preparing 400 g of gel:

Ingredient Weight/Volume Pentoxifylline 16 g Carbomer 940  4 g Propyleneglycol 20 ml Water q.s 400 g of gel Triethanolamine q.s pH (6-6.5)approx. 1.5-2 ml Propylparaben sufficient amount Methylparabensufficient amount

Water, propylene glycol and preservatives were introduced in a recipientwith stirring. The mixture was kept under stirring until completedissolution. Pentoxifylline was incorporated to the previous solutionand stirred until completing the dissolution.

Carbomer was then incorporated under vigorous stirring and the mixturewas left to settle for 24 h. After this time, the pH was adjusted withtriethanolamine to a value comprised between 6 and 6.5.

The gel obtained had a pentoxifylline content of 4% by weight. This gelwas packaged in a sterile tube type recipient which contained 10 g ofgel and which was provided with a vaginal applicator.

EXAMPLE 3 Assay of the Effectiveness of Pentoxifylline in the Treatmentof Couples with Infertility

The effectiveness of intravaginal administration of pentoxifylline ininfertility treatment was assayed in a group of 20 couples selectedaccording to the same criteria where the would have been susceptible toconjugal artificial insemination, i.e., they were unable to achievepregnancy after at least a one year period of maintaining sexualrelationships without protection,

Three single-doses of pentoxifylline gel of 10 g each obtained accordingto the method described in Example 1 were administered to said coupleswith the following indications for self-administration: the couple musthave sexual intercourse with vaginal ejaculation within the days ofmaximum fertility, and must introduce the gel in the vaginal cavityimmediately after coitus with the applicator provided for such purpose,remaining in a supine position for at least one hour being advisable.

The most fertile days were determined by cervical mucus test, vaginalultrasound, or ovulation test.

An ovulation inducer, clomiphene or purified human gonadotrofin,irrespectively, was simultaneously administered to 6 of the couples.

The gel was administered in 3 different cycles or in several days of thesame cycle.

A meeting was conducted with the patients between 15 and 20 hours aftereach administration and a microscopic examination of the endocervicalexudate was performed. It was observed in all cases that:

-   -   an improvement in sperm quality in terms of motility, both in        cases of asthenozoospermia and in cases of normospermia.    -   a significant number of type A sperm according to the WHO        classification.    -   an improvement in cervical mucus characteristics, in terms of        its filancia, transparency and leukocytic diathesis.

Among the 20 couples transvaginally treated with pentoxifylline, 4pregnancies were achieved, i.e., an effectiveness of 20%, which issignificantly greater than that achieved by conjugal artificialinsemination (14.7%).

Side effects due to the treatment were not observed in any case.

1. A phosphodiesterase inhibitor for use in the treatment of coupleswith infertility administered transvaginally.
 2. The phosphodiesteraseinhibitor for use according to claim 1, characterized in that it isselected from the group consisting of a phosphodiesterase 1 (PDE1)inhibitor, a phosphodiesterase 3 (PDE3) inhibitor, a phosphodiesterase 4(PDE4) inhibitor and a non-selective phosphodiesterase inhibitor, and acombination thereof.
 3. The phosphodiesterase inhibitor for useaccording to claim 2, characterized in that it is selected from thegroup consisting of pentoxifylline, rolipram, milrinone and ibudilast.4. The phosphodiesterase inhibitor for use according to claim 3,characterized in that it is pentoxifylline.
 5. The phosphodiesteraseinhibitor for use according to claim 1, characterized in that theinfertility is substantially caused by male infertility.
 6. Thephosphodiesterase inhibitor for use according to claim 5, characterizedin that the male infertility is due to anomalies in semencharacteristics.
 7. The phosphodiesterase inhibitor for use according toclaim 6, characterized in that the male infertility is due toasthenozoospermia.
 8. The phosphodiesterase inhibitor for use accordingto claim 1, characterized in that the dose of the phosphodiesteraseinhibitor is comprised between 200 mg and 800 mg in each administration.9. The phosphodiesterase inhibitor for use according to claim 1,characterized in that the phosphodiesterase inhibitor is administered incombination with an ovulation-inducing drug.
 10. The phosphodiesteraseinhibitor for use according to claim 1, characterized in that thephosphodiesterase inhibitor is administered before and/or after coitus.11. The phosphodiesterase inhibitor for use according to claim 1,characterized in that the treatment is applied as a complement to theartificial insemination technique.
 12. The phosphodiesterase inhibitorfor use according to claim 1, characterized in that it is administeredin the form of a pharmaceutical composition comprising aphosphodiesterase inhibitor and at least one pharmaceutically acceptableexcipient.
 13. The phosphodiesterase inhibitor for use according toclaim 12, characterized in that the pharmaceutical composition is in theform of an ovule, vaginal suppository, vaginal tablet, cream, ointment,paste, gel or foam.
 14. The phosphodiesterase inhibitor for useaccording to claim 13, characterized in that the composition is in theform of gel, ointment or cream.
 15. The phosphodiesterase inhibitor foruse according to claim 14, characterized in that the composition is inthe form of gel.
 16. A pharmaceutical composition in the form ofhydrophilic gel for transvaginal administration comprising aphosphodiesterase inhibitor, a polyhydroxy alcohol, water, a carbomerand an alkaline agent.
 17. The composition according to claim 16,characterized in that the phosphodiesterase inhibitor is selected fromthe group consisting of a phosphodiesterase 1 (PDE1) inhibitor, aphosphodiesterase 3 (PDE3) inhibitor, a phosphodiesterase 4 (PDE4)inhibitor and a non-selective phosphodiesterase inhibitor, and acombination thereof.
 18. The composition according to claim 17,characterized in that the phosphodiesterase inhibitor is selected fromthe group consisting of pentoxifylline, rolipram, milrinone andibudilast.
 19. The composition according to claim 18, characterized inthat the phosphodiesterase inhibitor is pentoxifylline.
 20. Thecomposition according to claim 16, characterized in that the polyhydroxyalcohol is selected from the group consisting of propylene glycol,dipropyleneglycol, glycerin, 1,2,6-hexanetriol, sorbitol, polyethyleneglycol 100 (PEG100), polyethylene glycol 200 (PEG200), polyethyleneglycol 300 (PEG300) and polyethylene glycol 400 (PEG400).
 21. Thecomposition according to claim 20, characterized in that the polyhydroxyalcohol is propylene glycol.
 22. The composition according to claim 16,characterized in that the carbomer has a viscosity comprised between25000 and 700000 mPa·s determined in an aqueous carbomer solution at0.5% by weight/volume and at a pH value comprised between 6 and
 11. 23.The composition according to claim 22, characterized in that thecarbomer has a viscosity comprised between 40000 and 60000 mPa·sdetermined in an aqueous carbomer solution at 0.5% by weight/volume andat pH comprised between 6 and
 11. 24. The composition according to claim16, characterized in that the alkaline agent is selected from the groupconsisting of L-lysine, L-arginine, borax, potassium hydroxide, sodiumhydroxide, ammonia, sodium bicarbonate, aminomethylpropanol ,tetrahydroxypropylethylenediamine, tromethamine, ethoxylated cocoamine(cocamine PEG15), diisopropanolamine, triisopropanolamine, andtriethanolamine.
 25. The composition according to claim 24,characterized in that the alkaline agent is triethanolamine.
 26. Thecomposition according to claim 16, characterized in that the proportionof the phosphodiesterase inhibitor by weight is comprised between 2% and10%.
 27. The composition according to claim 26, characterized in thatthe composition comprises a phosphodiesterase inhibitor in a proportionby weight comprised between 2% and 10%, propylene glycol in a proportionby weight comprised between 2% and 15%, carbomer in a proportion byweight comprised between 0.5% and 2%, triethanolamine in a proportion byweight comprised between 0.1% and 1% and water in a proportion by weightcomprised between 75% and 95%.
 28. The composition according to claim16, characterized in that the composition has a pH comprised between 5.5and 7.5.
 29. A kit characterized in that it includes the compositionaccording to claim 16 and instructions for administrating same.
 30. Thekit according to claim 29, characterized in that it includes threesingle-doses of phosphodiesterase inhibitor between 200 mg and 800 mg ineach of them.